Detection of supernova neutrinos by neutrino-proton elastic scattering

We propose that neutrino-proton elastic scattering, $\nu +\overrightarrow{p}\nu +p,$ can be used for the detection of supernova neutrinos in scintillator detectors. Though the proton recoil kinetic energy spectrum is soft, with $T_p\simeq {2E}_{\nu }^2{/M}_p,$ and the scintillation light output from slow, heavily ionizing protons is quenched, the yield above a realistic threshold is nearly as large as that from ${\overline{\nu }}_e+\overrightarrow{p}{e}^{+}+n.\mathrm{}$ In addition, the measured proton spectrum is related to the incident neutrino spectrum, which solves a long-standing problem of how to separately measure the total energy and temperature of ${\nu }_{\mu },$ ${\nu }_{\tau },$ ${\overline{\nu }}_{\mu },$ and ${\overline{\nu }}_{\tau }.$ The ability to detect this signal would give detectors like KamLAND and Borexino a crucial and unique role in the quest to detect supernova neutrinos.